5 

Cop  5 
G-3 


BULLETIN  OF 

ILLINOIS  COAL  MINING  INVESTIGATIONS 

COOPERATIVE  AGREEMENT 

Issued  bi-monthly 
VOL.  I  July,  1914  No.  2 

State  Geological  Survey 

Department  of  Mining  Engineering,  University  of  Illinois 

U.  S.  Bureau  of  Mines 


BULLETIN  5 

Coal  Mining  Practice 

IN 

District  I  (Longwall) 


BY 

S.  O.  ANDROS 

Field  Work  by  S.  O.  Andros  and  J.  J.  Rutledge 


Published  by 

University  of  Illinois 

Urbana,  Illinois 


(Application  for  entry  as  second-class  matter  at  the  postoflice,  at  Urbana,  111-,  pend/np:) 


The  Forty -seventh  General  Assembly  of  the  State  of  Illi- 
nois, with  a  view  of  conserving  the  lives  of  the  mine  workers 
and  the  mineral  resources  of  the  State,  authorized  an  investiga- 
tion of  the  coal  resources  and  mining  practices  of  Illinois  by 
the  Department  of  Mining  Engineering  of  the  University  of 
Illinois  and  the  State  Geological  Survey  in  cooperation  with 
the  United  States  Bureau  of  Mines.  A  cooperative  agreement 
was  approved  by  the  Secretary  of  the  Interior  and  by  repre- 
sentatives of  the  State  of  Illinois. 

The  direction  of  this  investigation,  is  vested  in  the  Director 
of  the  United  States  Bureau  of  Mines,  the  Director  of  the  State 
Geological  Survey,  and  the  Head  of  the  Department  of  Mining 
Engineering,  University  of  Illinois,  who  jointly  determine  the 
methods  to  be  employed  in  the  conduct  of  the  work  and  exercise 
general  editorial  supervision  over  the  publication  of  the  results, 
but  each  party  to  the  agreement  directs  the  work  of  its  agents 
in  carrying  on  the  investigation  thus  mutually  agreed  on. 

The  reports  of  the  investigations  are  issued  in  the  form  of 
bulletins,  either  by  the  State  Geological  Survey,  the  Depart- 
ment of  Mining  Engineering,  University  of  Illinois,  or  the 
United  States  Bureau  of  Mines.  For  copies  of  the  bulletins 
issued  by  the  State  and  for  information  about  the  work,  address 
Coal  Mining  Investigations,  University  of  Illinois,  Urbana,  111. 
For  bulletins  issued  by  the  United  States  Bureau  of  Mines, 
address  Director,  United  States  Bureau  of  Mines,  Washington, 
D.C. 


3  3051  00006  3739 


ILLINOIS 
COAL  MINING  INVESTIGATIONS 

COOPERATIVE   AGREEMENT 


State  Geological  Survey 

Department  of  Mining  Engineering,  University  of  Illinois 

U.  S.  Bureau  of  Mines 


BULLETIN  5 

Mining  Practice 

IN 

District  I  (Longwall) 


BY 


S.  O.  ANDROS 

Field  Work  by  S.  O.  Andros  and  J.  J.  Rutledge 


Urbana 

University  of  Illinois 

19  14 


19  14 


CONTENTS 


PAUE 

Introduction 7 

Description  of  bed 10 

System  of  mining 12 

Work  at  the  face 22 

Ventilation 27 

Timbering 32 

Haulage 36 

Hoisting 38 

Preparation  of  coal 40 


—2  G 


ILLUSTRATIONS 


NO.  PAGE 

1.  Map  showing  area  of  District  I Frontispiece 

2.  Plan  of  longwall  mine 12 

3.  Entries  in  shaft  pillar 13 

4.  Pack  walls  around  shaft  pillar 14 

5.  Elliptical  shaft  pillar 16 

6.  Entry  in  mine  with  no  shaft  pillar 17 

7.  Plan  of  mine  with  auxiliary  permanent  entries 18 

8.  Method  of  working  panel  longwall 19 

9.  Roof  breaks 20 

10.  Diversion  of  face  around  a  closed  place 21 

11.  Location  of  march  props 22 

12.  Mining  in  fireclay 23 

13.  Props  at  working  face 23 

14.  Plan  showing  direction  of  ventilating  current 27 

15.  An  entry  closely  timbered 30 

16.  Cog  built  of  props 31 

17.  Sketch  of  branch  cog 32 

18.  A  typical  lye 33 

19.  Circular  hoisting  shaft 34 

20.  Amount  of  "company  brushing"  necessary  after  subsidence 35 

21.  Typical  shaft  bottom 36 

22.  Receiving  hopper  at  shaft  bottom 37 

23.  Skip  adjusted  to  hoist  men 38 

24.  Tandem  cage 39 

25.  Typical  surface  plant 41 


TABLES 


No.  PAGE 

1.  General  data  by  counties 8 

2.  Comparative  statistics  for  the  State  and  for  District  I  for  the  year  ended,  June  30, 1912 8 

3.  Physicial  characteristics  of  bed 11 

4.  Dimensions  of  workings 19 

5.  Blasting 25 

6.  Comparison  of  accidents  in  District  I  and  in  all  other  districts  combined 26 

7.  Per  capita  production  of  employees 27 

8.  Comparative  mine  temperatures 28 

9.  Temperature  readings  near  gob  fire 29 

10.  Comparison  of  longwall  and  room-and-pillar  rib  dust  of  haulage  ways 30 

11.  Ventilating  equipment 31 

12.  Cost  of  mine  timbers 35 

13.  Underground  haulage 37 

14.  Hoisting  equipment 39 

15.  Tipple  equipment 40 

16.  Power  plant  equipment 42 


Fig.  1.    Map  showing  area  of  District  I.    (Shaded  portion).    Drawn  by  F.  H.  Kay 


BULLETIN  OF 
ILLINOIS  COAL  MINING  INVESTIGATIONS 

COOPERATIVE  AGREEMENT 

Issued  bi-monthly 
Vol.   I  July,   1914  No.   2 

MINING  PRACTICE  IN  DISTRICT  I  (LONGWALL) 

BY  S.  O.  ANDROS 
Field  work  by  S.  O.  Andros  and  J.  J.  Rutledge 


INTRODUCTION 

This  is  the  only  field  in  the  United  States  where  longwall  mining 
produces  any  considerable  tonnage  of  coal,  although  in  a  few  states  this 
method  is  practiced  to  a  limited  extent.  The  Longwall  District,  as 
shown  in  fig.  1,  includes  all  longwall  mines,  thirty-six  in  number,  work- 
ing bed  No.  2  of  the  Illinois  Geological  Survey  correlation  in  Will, 
Woodford,  Putnam,  Marshall,  LaSalle,  Grundy,  and  Bureau  counties, 
and  is  District  I  of  the  Illinois  Coal  Mining  Investigations.  A  detailed 
description  of  the  districts  into  which  the  State  has  been  divided  and  of 
the  method  of  collecting  data  from  which  this  bulletin  was  written  is 
contained  in  Bulletin  I,  A  Preliminary  Report  on  Organization  and 
Method. 

The  coal  produced  by  the  longwall  mines  during  the  fiscal  year  ended 
June  30,  1912,  totaled  5,032,346  tons,1  or  s.1  per  cent  of  the  total  coal 
production  of  Illinois.  Xo  undercutting  machines  are  used  in  these 
mines.  The  coal  mines  of  the  district  have  11,631  employees,  14.7  per 
cent  of  the  total  number  in  the  coal  mines  of  the  State.  Bureau  County 
with  1,664,092  tons  produced  in  longwall  mines  leads  l he  counties  of  the 
district.  On  account  of  the  initial  expense  of  opening  a  mine  to  be 
operated  on  the  longwall  system  only  two  local  mines  are  found  in  the 
district,  all  others  being  shipping  mines. 

These  longwall  mines  had  an  average  of  20!)  days  of  active;  opera- 
tion during  the  year  ended  June  30,  L912,  as  compared  with  an  average 
of  160  days  for  all  mines  in  the  State.  The  average  daily  production 
of  the  district  is  24,078  tons. 

Table  1  gives  general  data  tabulated  by  comities  on  the  longwall 
mines  of  the  district.  Table  2  shows  comparative  statistics  for  the  dis- 
trict and  for  the  State,  representing  the  year  ended  June  30,   1912. 

1  Thirty-first  Annual  Coal  Report  of  Illinois. 

3  G 


COAL    MINING    INVESTIGATIONS 


Table  1. — General  Data  by  Counties1 


County 


Num- 
ber of 
mines 


8  I 


C  b3  a> 

.a  <u  - 
a  >>- 


OS 

3 

A 

g 

9 

o 

"3. 

CD 
0) 

o 

o 

39 

^ 

>> 

X 

on 

■gg 

c3 

T3 

fe.8 

d 

03 

S3 

11 

>*> 

a  a 

to  42 

<J 

* 

* 

w 

Haulage 


Number  of  n  ines 
using — 


So 


Acci- 
dents 
to  em- 
ployees 


Bureau . . . 
LaSalle... 
Grundy.. 

Will 

Putnam.. 
Marshall. . 
Woodford. 


Total  for  Dist.  I    34 


1,664,092 
1, 158,  767 
742, 606 
179,001 
716, 531 
387, 463 
183, 896 


5, 032, 346 


*209 


226 

3,901 

189 

2,924 

211 

1,661 

211 

429 

244 

1,354 

228 

939 

212 

423 

11,631 


251 
312 
110 
31 

84 


912 


5,826 
5,282 


11,108 


29 


196 


1  Compiled  from  the  Thirty-first  Annual  Coal  Report  of  Illinois. 
*  Averaged  by  mines;  not  by  counties. 


Table  2. — Comparative  Statistics  for  the  State  and  for  District  I  for  the 
Year  Ended  June  30,  19121 


District  I 
(all  mines) 


State 
(all  mines) 


Per  cent 


Total  production 

Average  dailty  tonnage 

Average  days  of  active  operation 

Number  days  of  work  performed  in  1912 

Total  employees 

Number  surface  employees 

Number  underground  employees 

Number  underground  employees  per  each  surface  employee 

Number  tons  mined  per  day  per  employee 

Number  tons  mined  a  day  per  surface 

Number  tons  mined  a  day  per  underground  employee 

Number  fatal  accidents 

Per  cent  from  falling  coal  or  rock 

Per  cent  from  pit  cars 

Per  cent  from  explosives 

Number  deaths  per  one  thousand  employees 

Number  tons  mined  to  each  life  lost 

Number  non-fatal  accidents 

Per  cent  from  falling  coal  or  rock 

Per  cent  from  pit  cars 

Per  cent  from  explosives 

Number  injuries  per  one  thousand  employees 

Number  tons  mined  to  each  man  injured 


5, 032, 346 

24, 078 

209 

2,  430, 879 

11,631 

912 

10,  719 

11.8 

2.1 

26.3 

2.3 

12 

58.3 

16.6 

16.6 

1.0 

419,362 

196 

67.8 

21.9 

1.0 

16.8 

25, 675 


12, 


57,514,240 

359,  464 

160 

705,  760 

79,411 

7,049 

72, 362 

10.3 

4.5 

50.9 

4.9 

180 

54.4 

18.8 

7.2 

2  3 

319,524 

800 

45.5 

26.3 

2.6 

10.1 

71,893 


8.7 
6.6 


19.1 
14.7 
12.9 
14.8 


24.5 


1  Compiled  from  the  Thirty-first  Annual  Coal  Report  of  Illinois. 

Acknowledgments  of  assistance  are  due  to  the  mine  operators  of  the 
district  who  very  courteously  granted  access  to  their  mines  and  who 
freely  supplied  whatever  information  was  requested;  to  the  superintend- 
ents and  managers  of  the  mines  who  accompanied  the  engineers  in  their 
inspections  and  who  helped  obtain  desired  information;  and  especially 
to  the  following  individuals  who  rendered  conspicuous  service  by  fur- 
nishing much  supplemental  information  and  by  suggesting  alterations 
in  the  report  for  its  improvement :     Mr.  Gordon  Buchanan,  President, 


INTRODUCTION  lJ 

Wilmington  Star  Mining  Company;  Mr.  E.  T.  Bent,  President,  Oglesby 
Coal  Company;  Mr.  H.  S.  Hazen,  General  Manager,  and  Mr.  C.  C.  Swift, 
General  Superintendent,  LaSalle  County  Carbon  Coal  Company;  Mr. 
S.  M.  Dalzell,  General  Manager,  Spring  Valley  Coal  Company;  Mr.  J.  A. 
Ede,  Consulting  Engineer ;  Mr.  John  Dunlop,  State  Inspector  of  Mines ; 
Mr.  C.  H.  Herbert,  General  Superintendent,  Chicago,  Wilmington  and 
Vermilion  Coal  Company. 

This  district  was  the  first  to  be  developed  in  Illinois  and  for  many 
years,  by  reason  of  its  geographical  position,  nearly  all  the  interstate 
shipments  of  Illinois  coal  to  the  northwest  came  from  its  mines.  On 
account  of  the  greater  cost  of  production,  the  coal  from  this  field  cannot 
move  either  to  the  east  or  south  toward  other  mining  districts.  It  is 
estimated  that  the  average  cost  of  produuction  in  this  district  is  $1.65 
per  ton.  With  the  development  of  the  great  fields  in  southern  Illinois 
and  Indiana  the  production  of  the  district  has  decreased  and  few  mines 
have  been  opened  in  recent  years. 


10 


COAL    MINING    INVESTIGATIONS 


DESCRIPTION  OF  COAL  BED 


In  the  longwall  mines  of  District  I  the  No.  2  bed  of  the  Illinois 
Geological  Survey  correlation  varies  in  thickness  from  2  feet  8  inches  to 
4  feet,  with  an  average  of  3  feet  2  inches.  The  coal  is  used  extensively 
for  domestic  purposes  as  well  as  in  industrial  plants.  An  average  analy- 
sis obtained  from  33  face  samples  from  the  11  mines  examined  is  given 
below : 

Average  Coal  Analysis  of  the  District 


Number  samples 

Proximate  analysis  of  coal — First:    "As 

received"  with  total  moisture.    Second: 

"Dry"  or  moisture  free 

Sulphur 

B.  t.  u. 

Unit 
coal 

Moisture 

Volatile 
matter 

Fixed 
carbon 

Ash 

B.  t.  u. 

33 

/     16. 18 
\       Dry 

38.83 
46.33 

37.89 
45.21 

7.08 
8.45 

2.89 
3.45 

10,981 
13, 101 

14, 528 

The  chief  physical  characteristic  of  the  coal  in  this  district  is  the 
fine  lamination  of  alternately  bright  and  dull  coal.  On  account  of  these 
laminations  the  luster  is  not  so  pronounced  as  that  of  the  coal  from  the 
No.  6  seam ;  but  this  aspect  is  not  due  to  impurities.  The  persistent  dirt 
and  sulphur  bands  of  No.  6  are  absent,  but  in  places  are  thin  bands  of 
flat  or  lenticular  pyrites.  There  is,  however,  no  regularity  in  the  distri- 
bution at  any  horizon  of  the  layers  of  pyrites  or  of  the  local  bands  of 
pyritous  mother  coal  and  dirt  bands.  The  thickness  of  these  various 
layers  of  impurities  varies  from  y2  inch  to  4  inches. 

The  LaSalle  anticline  which  runs  in  a  general  northwest-southeast 
direction  divides  the  district  into  two  fields  with  slightly  different  phy- 
sical conditions:  the  Wilmington  on  the  east  and  the  LaSalle,  locally 
called  the  Third  Vein  field,  on  the  west.  The  coal  lies  at  greater  depth 
on  the  west  of  the  anticline  where  it  has  350  to  550  feet  of  cover. 

The  immediate  roof  in  the  Wilmington  field  is  usually  a  smooth 
gray  shale,  called  "soapstone"  by  the  miners.  In  places  sandstone  forms 
the  roof  material  and  causes  difficulty  in  brushing.  In  the  LaSalle  field 
the  roof  is  generally  a  gray  shale,  free  from  grit  but  containing  small 
flattened  nodules  of  ironstone  which  make  difficult  the  manufacture  of 
brick  from  the  roof  material. 

Near  the  anticline  the  immediate  roof  is  in  some  portions  a  gray, 
calcareous  shale,  called  "soapstone";  in  others,  a  black,  carbonaceous 
shale.  The  black  shale  is  generally  laminated  and  commonly  includes 
"niggerheads"  of  pyritous  material.     It  is  harder  than  the  gray  shale. 


DESCRIPTION    OF    COAL    BED 


11 


Iii  the  Wilmington  field  a  dark-gray  fireclay  generally  lies  directly 
under  the  coal  and  varies  in  thickness  from  a  few  inches  to  several  feet. 
The  clay  heaves  badly  under  pressure  when  wet.  In  some  localities  iron- 
stone balls  and  root  remains  have  been  found  embedded  in  the  clay. 
In  the  La  Salle  field  the  coal  is  generally  underlain  by  fireclay,  but  in 
parts  of  some  mines  a  hard  sandstone  lies  directly  beneath  the  coal. 

Generally  bed  No.  2  in  this  district  lies  nearly  flat  or  is  slightly 
rolling,  but  on  the  LaSalle  anticline  it  dips  as  much  as  51  degrees. 

Table  3  gives  data  on  the  physical  characteristics  of  the  bed,  roof, 
and  floor  for  each  mine  examined. 


Table  3. — Physical  Characteristics  of  Bed. 


Average 

No. 

thickness 

mine 

of 

seam   in 

feet 

Immediate  roof 

Location  of  bands 

Nature  of  floor 

1 

3^ 

2 

31 

3 

V, 

4 

31 

5 

3 

6 

3 

7 

3 

8 

31 

9 

3i 

0 

V, 

LI 

2f 

Gray  shale   and   black 
shale. 


Gray  shale  and  black 
shale. 

Gray  shale  and  black 
laminated  shale  with 
many  nigger-heads. 


Gray  shale. 


Gray  shale  and  black 
shale;  sandstone  in 
small  areas. 

Sandy  gray  shale. 


Gray  shale. 


(Gray   shale   and   black 
shale. 

Gray  shale  and   black 
shale. 


Gray  shale  and  lamin- 
ated black  shale.  Nig- 
ger heads  of  pyrites  in 
the  black  shale. 

Gray  shale. 


A  pyritous  clay  band  averag- 
ing two  inches  in  thickness 
under  the  gray  shale  only. 

Irregular  local  bands  of  pyri- 
tes mixed  with  mother  coal. 

A  persistent  band  of  sulphur 
balls  twenty-one  inches  from 
top  of  coal. 


Irregular  bands  of  pyrites  al 
varying  distances  from  floor. 

Bands  of  pyrites  of  irregular 

horizontal  and  vortical  ex- 
tent in  limited  areas. 

A  few  bands  of  pyrites  and 
mother  coal. 


Numerous   bands  of  pyrites 

and  mother  coal  of  irregular 
horizontal  extent  between 
roof  and  coal;  bands 'freeze" 
to  the  coal. 

A  few  pyrite  lenses  iu  the 
black  shale. 

Lenses  of  pyrites  m  layers 
with  the  longer  axis  of  the 
lense  parallel  to  the  bedding 
plane. 

Irregular  layers  of  pyritous 
mother  coal. 


Occasional  lenses  of  pyrites. 


Gray,  micaceous,  clayey  sand- 
stone which  grades  into 
fireclay. 

Fireclay  bedded  in  irregular, 
thin,  inclined  layers. 

Hard,  dark-gray  fireclay  con- 
taining very 'little  carbon- 
aceous matter  with  embed- 
ded ironstone  balls;  a  hard 
sandy  shale  in  places  im- 
mediately below  the  coal. 

Fireclay  soft  in  some  places, 
sandy  and  hard  in  others. 

Sandy  fireclay. 


Soft    fireclay;    heaves    badly 

when   wet   and  under   pres- 
sure. 

Dark-gray  fireclay  containing 
a   small   quantity    of   root 

remains. 


Fireclay:  at  the  depth  of  loin- 
feet  contains  boulders. 

Soil    fireclay   subject    to    bad 
heaving  when  wet. 


Hard,  dark-gray  fireclay  ap- 
proaching shale  in  charac- 
ter; plant  impressions  vis- 
ible. 


Soft  fireclay. 


A  detailed  and  comprehensive  report  on  the  geology  of  this  district 
is  in  preparation,  and  will  be  published  later  as  a  separate  bulletin. 


12 


COAL    MINING    INVESTIGATIONS 


SYSTEM  OF  MINING 


Every  mine  examined  in  this  district  is  worked  according  to  the 
longwall  advancing  system,  and  whether  the  coal  is  reached  by  a  shaft, 
slope,  or  drift,  the  entire  seam  is  removed  during  the  advance,  the  work 
progressing  in  a  long  continuous  face  as  shown  in  fig.  2. 


Fig/2.     Plan  of  longwall  mine.    (After  Swift) 


MINING   PRACTICE 


13 


In  an  Illinois  shaft  mine  operated  on  the  longwall  system  the 
workings  may  be  likened  to  a  wheel.  The  hub  may  represent  either 
the  pillar  of  coal  left  to  preserve  the  air  and  hoisting  shafts,  or  the 
building  about  these  shafts  if  no  shaft  pillar  is  left  for  roof  support. 
The  haulage  ways  maintained  through  the  gob  represent  the  spokes  of 
this  wheel,  and  the  working  face  represents  the  rim.  For  some  mines 
this  wheel  would  be  elliptical  rather  than  circular.  In  a  slope  or  in  a 
drift  mine  in  which  the  longwall  system  is  used  the  workings  could  be 
shown  by  one-half  of  this  wheel,  either  a  semi-circle  or  a  semi-ellipse. 


Fig.  3.    Entries  in  shaft  pillai 


The  greatest  difficulty  in  stalling  longwall  operations  is  in  leaving 
the  shaft  pillar  and  establishing  the  longwall  face.  A  common  method 
of  procedure  in  this  district,  after  the  hoisting  shaft  and  air  shaft  have 
reached  the  coal,  is  to  drive  a  main  entry,  as  shown  in  fig.  -'!,  from  each 
side  of  the  hoisting  shaft  for  a  distance  of  about  225  5feet.  From  the 
airshaft  two  entries  arc  driven  in  opposite  directions  at  right  angles  to 
the  main  entry,  and  arc  continued   until  each  entry   reaches  that   point 


14 


COAL    MIXING    INVESTIGATIONS 


where  a  side  of  the  shaft  pillar  is  to  be  blocked  out.  The  air  shaft  may 
be  offset  from  the  line  of  this  entry  as  shown  in  fig.  2.  The  shaft  pillar 
is  now  usually  blocked  out  by  driving  a  narrow  entry  around  it,  "called 
the  entry-around-pillar."  Xo  formula  is  used  to  determine  the  size 
of  shaft  pillar  necessary  with  a  given  thickness  of  overlying  strata,  ami 
pillars  are  found  in  the  district  as  small  as  60  feet  square  where  the  coal 
has  100  feet  of  cover.  Large  pillars  are  desirable  because,  in  addition 
to  preserving  the  integrity  of  the  shafts,  they  provide  for  more  mining 
places  when  operations  begin. 


Fig.  4.    Pack  walls  around  shaft  pillar 


A  critical  time  in  longwall  mining  is  when  the  first  roofbreak  occurs 
at  the  working  face.  The  roof  may  not  break  until  the  face  has  ad- 
vanced about  100  feet  from  the  shaft  pillar;  and  after  the  face  break  has 
taken  place  there  is  a  large  area  of  settling  roof  overhanging  from  and 
supported  by  the  shaftpillar.  Consequently  the  roof  will  break  at  the 
shaftpillar.  The  subsidence  of  roof  following  this  break  continues  vio- 
lently for  three  weeks  and  more  gradually  for  a  year.  Unless  the  entry- 
around-pillar  is  protected  by  a  packwall  or  coal  pillar,  it  will  be  closed 


MINING    PRACTICE  15 

by  this  first  violent  roofsubsidence.  After  the  entry-around-pillar  has 
been  established,  openings  9  feet  wide  as  shown  in  fig.  3,  which  is  a 
sketch  of  an  actual  shaft  pillar,  are  driven  into  the  coal  face  at  inter- 
vals usually  of  42  feet.  When  these  openings  have  progressed  15  feet, 
cuts  9  feet  wide  are  made  on  each  side  of  each  opening  at  a  right  angle 
and  are  driven  until  the  cut  at  the  left  of  one  opening  meets  the  cut 
driven  from  the  right  of  the  one  adjacent.  These  cuts  serve  the  double 
purpose  of  establishing  the  longwall  face  and  of  leaving  a  15-foot  coal 
pillar  for  the  protection  of  the  entry-around-pillar. 

Sometimes  when  it  is  feared  that  the  coal  of  the  shaft  pillar  and 
entry  pillar  may  spall  off  into  the  roadway  a  strip  of  coal  15  feet  wide 
is  sliced  off  completely  around  the  shaft  pillar  as  shown  in  fig.  4  and  is 
replaced  by  a  pack  wall.  The  15-foot  pillar  left  for  entry  protection  is 
also  replaced  by  a  pack  wall.  From  the  time  when  both  hoisting  shaft 
and  air  shaft  reach  the  coal,  7  to  10  months  are  required  for  driving 
entries  through  the  shaft  pillar  and  for  blocking  it  out.  Actual  mining 
is  not  usually  begun  until  the  entries-around-pillar  are  connected,  inas- 
much as  there  is  no  direct  ventilation  before  the  entries  are  holed  through 
except  by  means  of  temporary  air-boxes  or  pipes. 

The  method  of  blocking  out  the  shaft  pillar  by  driving  narrow 
entries  around  it  is  in  general  use,  but  occasionally  entries  27  feet  wide 
are  driven  around  the  pillar,  and  two  pack  walls  are  built  as  the  entry 
advances.  One  pack  wall  12  feet  wide  is  built  alongside  the  shaft  pillar, 
and  one  6  feet  wide  on  the  future  longwall  face,  leaving  a  haulage  road 
9  feet  wide  between  the  two  walls.  The  accessary  openings  through  the 
walls  are  left  for  haulage. 

One  of  the  mines  examined  has  an  elliptical  shaft  pillar  as  shown 
in  fig.  5.  A  main  entry,  "A/'  was  driven  past  the  hoisting  shaft  parallel 
to  its  longer  dimension.  On  the  opposite  side  of  the  shafl  a  short  back 
entry  "B,"  was  driven  parallel  to  the  main  entry  and  at  each  -end  was 
turned  into  the  main  entry  at  a  point  far  enough  from  the  shaft  so  that 
a  trip  of  empty  cars  could  be  stored  on  each  side.  At  each  end  of  the 
shaft  a  cross-cut  connects  the  two  entries,  allowing  the  passage  of  mules. 
The  empty  cars,  bumped  off  the  cage  into  the  hack  entry  by  the  loaded 
cars,  arc  then  hauled  through  the  back  entry  and  into  the  main  entry 
at  a  point  beyond  the  end  of  any  trip  of  loaded  cars  which  may  he 
standing  at  the  bottom.  This  method  obviates  the  necessity  of  a  mam 
entry  wide  enough  for  double  tracks  and  saxes  much  timbering  at  the 
bottom.  From  the  hoisting  shaft  at  a  right  angle  to  the  main  entry 
the  entries  "C"  were  driven  to  the  boundary  of  the  pillar. 

In  nearly  all  new  mines  opened  in  the  district  a  pillar  of  coal  has 
been  left  around  the  hoisting  and  air  shafts,  hut  among  the  older  mines 
occasional  examples  are  found  where  no  coa]  has  been  left  to  support,  the 
roof;  a  total  coal  extraction  having  allowed  the  roof  around  the  shaft 
to  settle  gradually  till  roof  and  floor  meet.  When  no  shaft  pillar  is  to 
be  left  for  roof  support,  as  soon  as  the  hoisting  shaft  reaches  the  hot  torn 
of  the  coal  the  horned  set  is  placed  on  soft  wood  doorhead  posts,  about 
12  by  12  inches  in  size,  and  the  coal  is  removed  from  all  sides  of  the 
shaft.     The  space  left  by  the  removal  of  the  coal  is  filled  with  soft  wood 

—4  G 


16 


MIXING    PRACTICE 


17 


mining    rock. 


cogs  called  shanties,  and  with  packs  of  brushing  and 
Through  the  gob  a  7-foot  roadway  is  opened  up  from  each  side  and  from 
each  end  of  the  shaft.  The  roadway  props  are  sawed  off  at  the  top  an 
inch  at  a  time  as  the  roof  settles  and  new  cap  pieces  are  driven  in.  In 
some  cases  this  sawing  must  be  attended  to  daily  and  the  roadways 
brushed  every  few  days  to  keep  them  open.  As  the  roof  settles  the  packs 
and  shanties  are  compressed  and  squeezed  into  the  fireclay  till  roof 
and  floor  meet.  The  shaft  bottom  is  then  widened  and  timbered.  Fig. 
6  shows  in  a  mine  opened  without  leaving  a  shaft  pillar  of  coal  an  entry 
at  a  point  about  50  feet  from  the  hoisting  shaft.  This  entry  has  stood 
many  years  without  retimbering. 

The  advantages  claimed  for  removing  the  coal  around  the  shaft  are 
that  the  expense  of  timbering  the  bottom  is  reduced,  and  that  the  roof- 


Fig.  G.    Entry  in  mine  with  no  shaft  pillar 


weight  begins  sooner  to  ride  on  the  working  face.  Those  operators 
who  leave  coal  for  shaft  pillars  admit  these  advantages  but  reason 
that  the  uncertainty  of  being  abU  so  to  control  subsidence  thai  the  shafts 
will  not  be  thrown  out  of  plumb  when  the  pillar  is  removed  is  too  great. 
After  the  shaft  pillar  has  been  blocked  out  and  removed  and  the  longwall 
face  established  the  work  progresses  regularly  in  a  long  continuous  line. 
From  each  side  of  the  centers  of  the  openings  which  were  left  in  the  entry 
pillar  the  coal  of  the  face  is  removed.  In  order  to  provide  for  haulage 
from  all  parts  of  the  face  to  the  shaft,  roadways  9  feet  wide,  called 
rooms,  are  maintained  as  shown  in  fig.  5,  by  building  pack  walls  of  rock. 
These  rooms  are  continuations  of  the  openings  through  the  entry  pillar, 
and  the  pack  walls  protecting  them  are  usually  12  feet  thick.  When 
pack  walls  are  first  made  they  are  often  spaced  10  to  12  feet  apart  to 
allow  for  bulging  when  the  roof  weight  sets  on  them  which  causes  nar- 
rowing of  the  roadways.     A  track  is  laid  to  the  face  of  each  room.     In 


18 


COAL    MINING    INVESTIGATIONS 


order  to  save  the  expense  of  a  road  for  haulage  from  the  face  of  each 
room  to  the  main  entry  in  the  shaft  pillar,  cross  entries  maintained 
through  the  gob  by  pack  walls,  are  turned  off  near  the  shaft  pillar  as 
shown  in  fig.  2,  and  intersect  the  rooms  at  an  angle  of  45  degrees.  The 
second  set  of  cross  entries  is  usually  225  to  300  feet  from  the  first. 
This  distance  is  maintained  throughout  the  workings. 

This  form  of  longwall  working,  often  called  the  "Scotch  45-degree 
system,"  prevails  where  no  unusual  conditions  obtain,  but  various  mod- 
ifications of  the  system  are  found  where  the  seam  dips  steeply  or  where 
roof  and  floor  characteristics  necessitate  a  departure  from  the  usual 
method.     To  provide  a  better  haulage  from  the  face  in  one  mine  where 


Fig.  7.    Plan  of  mine  with  auxiliary  permanent  entries 


heavy  timbering  is  necessary,  entries  are  maintained  from  the  shaft  pillar 
as  shown  in  fig.  7  bisecting  each  quadrant  formed  by  the  four  main 
roadways,  making  eight  main  haulage  ways  in  the  mine.  From  both 
sides  of  these  eight  main  roads  at  225-foot  intervals  cross  entries  are 
maintained  at  an  angle  of  45  degrees.  When  the  cross  entries  from  ad- 
jacent permanent  roads  intersect,  one  entry  is  continued  and  the  other 
is  abandoned.  Every  1,700  feet  along  the  left  side  of  each  of  the  eight 
main  haulage  roads  is  turned  a  haulage  entry  permanently  timbered. 
Where  the  coal  seam  lies  in  the  LaSalle  anticline  its  dip  becomes 
as  steep  as  51  degrees,  and  the  methods  of  work  approach  those  of  metal- 


MINING   PRACTICE 


19 


liferous  mining.  While  the  general  longwall  system  of  main  and  cross 
entries  and  rooms  on  the  45-degree  plan  is  followed,  a  longwall  panel 
is  operated  at  the  face  as  shown  in  fig.  8.  The  coal  from  all  the  face 
below  a  cross  entry  is  thrown  on  a  sheetiron  chnte  down  which  it  slides 
to  the  entry  below.  The  chute  is  built  of  small  sheets  3  feet  wide  and 
8  feet  long  each  having  a  flat  hook  at  one  end  and  a  hole  at  the  other 


Fig.  8.     Method  of  working  panel  long  wall.     (After  Ede) 

to  receive  the  hook  of  the  nexl  sheet.  The  chute  is  moved  forward 
daily  as  the  face  progresses.  In  several  mines  cross  entries  are  driven 
off  at  an  angle  of  70  degrees  with  the  main  entries  for  the  purpose  of 
increasing  the  size  of  the  cog  buill  to  support  the  roof  over  the  switches 
at  the  junction  of  main  roadway  and  cross  entries.  Table  1  gives 
dimensions  of  workings  ai  each  mine  examined. 


Table  1. — Dimensions  of  Workings 


a 

A 

op 

•Q 

A& 

a*  a 

to 

Q 

I      I 

C  CO   tx, 

u  •''  9 

2V 


B  O 
c  n 

o  — 


%  ¥  £  a- 

A 


\\  Idth  of  roadways 
in  feet 


Main 


Cross 


Room 


.3.93 


1 

413 

2 

465 

3 

398 

4 

•546 

5 

135 

6 

100 

7 

200 

8 

300 

9 

Slope 

[<) 

480 

11 

530 

400  x   600 

225 

45 

250  x   250 

225 

45 

550  x   550 

240 

45 

No  pillar 

200 

70 

360  x   560 

275 

45 

150  x   300 

225 

45 

350  x   450 

45 

225 

45 

320 

30 

500  x   500 

225 

45 

600  x*3,600 

225 

45 

This  pillar  was  left  for  the  protection  of  three  hoisting  shafts. 


20 


COAL    MIXING    IXVESTIGATIOXS 


In  all  classes  of  longwall  operation  the  same  general  method  of 
filling  the  space  left  by  the  removal  of  the  coal  prevails.  The  rock 
obtained  from  brushing  the  roof,  that  which  remains  after  building  pack 
walls,  and  the  clay  obtained  from  undermining  the  coal  are  thrown  be- 
hind the  pack  walls  lining  the  roads.  The  space  between  the  pack  walls 
and  also  the  waste  material  itself  is  called  the  gob.  The  gob  area  is 
usually  filled  with  rock  and  clay  to  within  2  to  5  feet  of  the  coal  face. 
This  loose  rock  and  clay  helps  to  support  the  roof  and  control  the  roof 
weight  on  the  coal  face.  After  the  first  break  at  the  shaft  pillar  and 
face — if  the  gob  area  has  been  properly  filled  so  that  the  roof  weight 
rides  on  the  face  of  the  coal — other  roof  breaks  occur  every  2  inches  to 


Fig. 


Roof  breaks 


6  feet  parallel  to  the  coal  face  and  extending  upward  away  from  the  face 
and  toward  the  gob  as  the  face  advances.  See  fig.  9.  The  distance 
between  breaks  depends  principally  upon  the  character  of  the  roof  and 
the  packing  of  the  gob.  With  proper  packing  the  distance  between 
breaks  should  correspond  to  the  width  of  coal  brought  down.  At  the 
face  of  solid  coal  the  cracks  in  the  roof  are  difficult  to  see,  and  they  do 
not  become  easily  visible  until  the  face  has  advanced  4  to  5  feet. 

The  distance  to  which  these  mining  breaks  extend  into  the  roof 
depends  upon  the  roof  material,  but  they  rarely  extend  more  than  15  feet 
above  the  coal.  The  angle  made  by  these  breaks  varies  from  50  to  90 
degrees  from  the  horizontal,  depending  upon  the  roof  material  and  the 


MIXING    PEACTICE 


21 


rate  of  settling.  In  summer  when  the  face  progresses  slowly  the  cracks 
are  more  nearly  vertical. 

The  seam  in  the  district  is  thin  and  the  price  paid  the  miner  per 
ton  of  coal  mined  includes  brushing  the  roof  of  the  roadways  to  provide 
height  for  haulage.  In  the  La  Salle  field  the  miner  is  paid  90  cents  per 
ton  of  coal  mined  and  he  must  take  down  24  inches  of  roof  over  the  road- 
ways, but  any  subsequent  brushing  necessary  is  done  by  the  company. 
In  the  Wilmington  field  the  miner  is  paid  95  cents  per  ton  of  coal  mined, 
but  he  must  maintain  the  roof  of  his  roadway  4  feet  above  the  rail  be- 
tween a  point  40  feet  back  from  the  face  and  the  switch,  provided  this 
distance  does  not  exceed  300  feet.  He  is  not  required  to  clean  up  any 
fall  on  this  roadway  which  is  not  due  to  his  failure  to  secure  the  roof 
properly. 

In  each  of  the  mines  examined  squeezes  closing  the  working  place 
by  filling  them  with  roof  material  have  occurred.     A  squeeze  takes  place 


Fig.  io.    Diversion  of  face  around  a  closed  place 


when  a  room  is  driven  ahead  of  adjacenl  rooms;  when  a  room  is  allowed 
to  lag  behind;  and  most  commonly  when  defective  pack  walls  have  been 
built  and  the  gob  area  lias  not  been  sufficiently  filled  with  waste.  The 
amount  of  waste  necessary  to  he  thrown  hack  into  the  gob  to  insure 
safety  from  squeeze  depends  upon  the  conditions  in  the  rooms,  such  as 
the  thickness  and  character  of  the  coal,  the  nature  of  the  roof  and  the 
method  of  mining.  The  waste  should  fill  the  gob  sufficiently  Io  allow 
the  roof  to  come  down  gradually  without  breaking  off  short  at  the  face 
of  the  pack  walls,  but  should  not  Jill  the  gob  so  completely  that  it  carries 
too  much  of  the  roof  ;ind  does  not  throw  enough  weighl  on  the  face  of 
the  coal.  The  better  (he  gob  is  packed,  the  hetter  the  coal  works.  The 
width  of  the  pack  wall,  called  "building,"  necessary  to  prevent  the  walls 
from  squeezing  ou1  and  filling  the  roadway  when  the  root'  weight  comes 


22 


COAL    MINING    INVESTIGATIONS 


on  them  depends  upon  local  conditions.  The  Third  Vein  District  Agree- 
ment between  the  Illinois  Coal  Operators'  Association  and  the  United 
Mine  Workers  of  America  in  Article  1  provides:  "The  miner  shall 
build  4  yards  of  wall  at  each  side^of  his  road,  and  if  he  has  more  rock 
than  is  required  therefor  he  shall  not  load  any  of  it  until  he  has  filled 
his  place  therewith.  In  case  the  miner  has  not  rock  enough  to  build  his 
4  yards  he  shall,  at  the  request  of  the  company,  begin  his  wall  4  yards 
from  the  roadside;  provided,  that  the  above  shall  not  prohibit  the 
miner,  at  his  option,  from  beginning  his  wall  at  any  greater  distance 
upon  the  request  of  the  company."  When  some  part  of  the  face  has 
been  allowed  to  lag  behind  and  the  working  face  has  squeezed,  the  area 
is  not  usually  cleaned  up,  but  the  face  is  diverted  to  pass  around  the 
squeezed  area,  sometimes  leaving  a  small  block  of  coal  in  the  gob  as 
shown  in  fig.  10. 

The  effect  of  the  subsidence  of  the  roof  upon  the  overlying  strata 
and  upon  the  surface  after  the  coal  has  been  removed  has  not  been 
clearly  determined.  Surface  subsidence  has  been  the  subject  of  extended 
litigation.  While  it  is  undoubtedly  true  that  there  is  subsidence  of  the 
strata  immediately  overlying  the  coal,  opinion  is  divided  as  to  the  extent 
of  this  subsidence.  There  are  not  sufficient  data  available  from  which 
to  formulate  a  general  rule  for  the  amount  that  results  from  mining 
seams  of  different  thicknesses  lying  at  different  depths  and  under  differ- 
ent kinds  of  cover.  In  only  one  of  the  mines  examined  was  surface 
subsidence  easily  apparent. 

WOEK    AT    THE    FACE 

Room  centers  at  the  longwall  face  are  usually  42  feet  apart.  Half- 
way between  the  center  of  the  road  head  of  each  room  and  the  center 
of  the  road  head  of  the  adjacent  rooms  a  prop  called  the  "march  prop" 
is  set  as  shown  in  fig.  11.     The  42  feet  of  coal  face  included  between 


• * (* —  42'— 

Fig.  11.     Location  of  march  props 


two  march  props  is  called  a  "place."  Until  recent  years  two  miners 
worked  at  every  place  in  all  longwall  mines,  but  at  present  on  account 
of  the  scarcity  of  labor  probably  one-half  of  the  places  in  longwall  mines 


MIXING    PRACTICE 


23 


contain  only  one  miner.    Upon  the  one  miner  or  two  miners,  as  the  case 
may  be,  assigned  to  a  place,  is  the  charge  of  proper  building  of  pack 


Fig.  12.     Mining  in  fireclay 


walls  along  the  roadway  of  the  room,  and  of  proper  gobbing  of  the  space 
between  the  marches. 


Fig.  13.    Props  at  working  face 


When  the  bed  is  underlain  by  fireclay,  beginning  at  the  center  of 
the  roadway  each  miner  picks  out  the  clay  under  the  coal  as  shown  in 


24  COAL    MINING   INVESTIGATIONS 

fig.  12  and  makes  an  undercut  8  to  12  inches  high.  This  undercut 
sometimes  extends  2  to  2%  feet  under  the  coal.  To  prevent  it  from 
falling  on  the  miner  while  he  is  undermining,  sprags  are  placed  against 
the  coal,  spaced  6  to  8  feet  along  the  face.  To  support  the  roof,  props, 
as  shown  in  fig.  13,  are  set  2  to  5  feet  from  the  face  and  are  spaced  6 
to  8  feet  apart.  With  an  average  depth  of  undermining,  a  good  miner 
can  undercut  about  20  feet  of  face  a  day  when  working  in  soft  clay 
8  to  12  inches  thick. 

When  a  car  is  to  be  loaded,  that  portion  of  the  coal  is  taken  which 
has  been  standing  longest  on  sprags.  These  are  knocked  away  from 
the  coal  with  a  sledge  and  if  the  gob  has  been  properly  filled  so  that 
the  roof  weight  is  riding  on  the  face,  the  coal  breaks  away  from  the 
roof  and  is  ready  for  loading.  If  the  coal  sticks  to  the  roof  and  does 
not  break  when  the  sprags  are  knocked  away,  it  is  pried  down  with 
wedges  driven  by  a  sledge  between  the  roof  and  the  coal. 

The  operators  in  the  district  report  that  under  reasonably  good 
conditions  of  longwall  mining,  approximately  80  per  cent  of  1 14-inch 
lump  is  produced ;  but  with  varying  physical  characteristics  of  roof,  coal, 
and  floor  modifications  of  mining  procedure  are  found.  These  modifi- 
cations may  be  disadvantageous  to  the  operator  by  increasing  the  amount 
of  slack  and  may  endanger  the  life  and  limb  of  the  miner  by  increasing 
the  number  of  falls  of  coal  and  roof. 

If  the  fireclay  usually  underlying  the  coal  is  absent  and  the  floor 
material  is  sandstone,  or  if  the  fireclay  is  much  over  18  inches  in  thick- 
ness, undermining  is  done  in  the  coal  itself.  The  amount  of  slack  made 
by  undermining  the  coal  is  large.  The  practice  is  further  undesirable 
in  that  it  increases  the  number  of  gob  fires  because  more  fine  coal  is 
thrown  into  the  gob  with  the  waste. 

To  save  time  and  labor  the  miner  often  neglects  to  support  the 
coal  on  sprags  until  the  usual  two  feet  of  under-mining  is  completed, 
but  he  makes  a  cut  4  to  8  inches  deep  and  pries  down  the  undermined 
coal  with  a  pick,  or  wedges  it  down.  This  method  does  not  allow  the 
slow  breaking  of  the  coal  by  roof  weight;  consequently  more  accidents 
occur,  and  more  slack  and  smaller  coal  result  than  when  full  undermin- 
ing is  insisted  upon.  Enforcement  of  spragging  would  be  a  distinct 
advantage  to  the  miner  and  to  the  operator.  The  disproportionate 
number  of  accidents  in  the  district  in  ratio  to  its  tonnage  would  be 
decreased,  and  10  to  15  per  cent  more  lump  coal  would  be  made  if 
proper  undermining  were  enforced. 

If  niggerheads  make  up  part  of  the  roof  and  if  the  floor  contains 
rolls,  explosives  are  used  to  bring  down  the  coal.  In  this  district  black 
powder  is  used  unnecessarily  in  several  mines.  The  effect  of  its  use  is 
illustrated  in  one  mine  where  owing  to  niggerheads  in  the  black  shale 
roof  the  coal  is  shot  down  in  a  small  section  of  the  mine.  Ten  per  cent 
more  slack  coal  results  in  the  section  where  shooting  is  necessary  than 
in  the  other  sections  of  the  mine.  The  roof  is  injured  by  the  blasts  and 
is  made  difficult  to  support  at  the  working  places.  Table  5  gives  data 
on  blasting. 


MINING    PRACTICE 


25 


Table  5 — Blasting 


No. 
mine 

Is  coal  shot  down? 

Size 

of 

powder 

Explosive  used  in 
brushing  roof 

Under- 
mining 

in 

clay  or 

coal 

Per 

cent  of 

lump  coal 

over  1} 

inchesj 

Drill  holes  in 
coal 

Diam- 
eter in 
inches 

Length 
in  feet 

1 

No 

None 

Both 

Clay 

..do 

Coal 

Clay 

..do 

80 

83 

79 

65 

70 

80 

*73 

*73 

Mine  run 

f83 

83 

2 

Under  nigger  heads 

Under  black  shale  only. . 
Yes 

FF  .... 
FF  .... 
FFF... 
FF  .... 

It 
If 

4 
5 

3 

4 

40  per  cent  dynamite. . 

5 

Yes 

40  per  cent  dynamite. . . 
..do 

4 

6 

No 

7 

Yes 

FF 

FF  .... 
FF  .... 

60  per  cent  dynamite. . . 

Black  powder 

35  per  cent  dynamite. . . 
30  per  cent  dynamite. . . 
45  per  cent  dynamite. . . 

..do 

..do 

..do 

Both 

..do 

H 
2" 
2£ 

4 

8 
9 

Under  black  shale  only. . 
Yes 

4 

10 

No 

11 

No 

t  Figures  furnished  by  operators. 
*  Over  1^  inches. 
f  Over  |  inch. 


No  longwall  undercutting  machines  are  used  in  this  district. 

Inasmuch  as  the  coal  seam  contains  many  pyrite  concretions  which 
if  thrown  into  the  gob  with  the  waste  or  built  into  the  pack  walls  might, 
it  is  believed,  cause  gob-fires,  an  attempt  is  made  to  separate  this  "sul- 
phur" from  the  shale  and  clay.  The  Third  Vein  District  Agreement 
between  the  Illinois  Coal  Operators'  Association  and  the  United  Mine 
Workers  of  America  provides  in  Article  VII  that  "no  sulphur  shall  be 
put  in  the  building  or  march  without  the  company's  permission.  When 
the  rock  is  loaded  out  the  sulphur  shall  be  loaded  with  it.  When  no 
rock  is  loaded  out  the  sulphur  shall  be  left  along  the  roadside,  except 
that  where  the  company  so  elects,  the  miner  shall  load  it  properly  and 
receive  therefor  15  cents  per  car,  if  the  average  coal  capacity  is  less  than 
1,500  pounds,  and  22-4/10  cents  per  car  where  larger  cars  are  used."  In 
spite  of  this  agreement  considerable  sulphur  is  thrown  in  the  gob. 

If  the  working  places  in  longwall  mines  are  properly  inspected  by 
face-bosses,  there  should  be  fewer  accidents  per  ton  of  coal  gained  or 
per  1,000  employees  than  in  room-and-pillar  mines  because  of  the  com- 
paratively small  amount  of  blasting.  Under  existing  conditions,  how- 
ever, the  contrary  is  true.  During  the  year  ended  June  30,  1912,  in 
this  district  15)(i  men  were  so  injured  as  to  lose  a(  least  30  days  work 
and  12  men  were  killed.  The  district  with  its  output  of  -y)32,346  tons 
for  the  fiscal  year  had  8.7  per  cent  of  the  product  ion  of  the  Stale. 
During  this  period  24.5  per  cent  of  the  non-fatal  accidents  in  coal  mines 
in  Illinois  occurred  in  the  district.  'This  apparently  enormous  dispor- 
portion  is  reduced  when  it  is  considered  that  a  very  small  tonnage  is 
produced  by  each  employee  per  day  in  the  longwall  field,  the  average 
number  of  tons  being  less  than  one-half  of  the  average  for  the  other 
districts  combined.  In  the  year  which  ended  dune  :>(),  1912,  the  average 
number  of  tons  of  coal  produced  per  employee  per  day  was  2.1  for 
District   I,  as  compared  with  4.0  for  all   the  other  districts  combined. 


26 


COAL    MINING    INVESTIGATIONS 


The  number  of  employees  consequently  is  out  of  proportion  to  the 
amount  of  coal  gained,  the  number  employed  in  the  district  being  14.7 
per  cent  of  all  employees  in  coal  mines  of  Illinois.  The  number  of  days 
of  active  operation  for  the  district  averaged  209,  as  compared  with  160 
for  the  State.  With  an  average  of  11,631  employees  working  209  days 
there  were  2,430,897  days  of  labor  performed.  This  number  is  19.1 
per  cent  of  the  total  for  the  State  as  a  whole.  It  is  seen,  therefore,  that 
its  24.5  per  cent  of  non-fatal  injuries  shows  careless  mining. 


Table  6. — Comparison  of  accidents  for  the  year  which  ended 
June   30,   1912 


District  I 


All  other 
districts  com- 
bined 


Number  fatal  accidents 

Per  cent  from  falling  coal  or  rock 

Per  cent  from  pit  cars 

Per  cent  from  explosives 

Number  deaths  per  one  thousand  employees. 

Number  tons  mined  for  each  life  lost 

Number  non-fatal  accidents 

^^  Per  cent  from  falling  coal  or  rock 

Per  cent  from  pit  cars 

'  Per  cent  from  explosives 

Number  injuries  per  one  thousand  employees 
Number  tons  mined  to  each  man  injured 


168 

54.2 

19.1 

6.6 

2.5 

313, 124 

604 

38.2 

27.7 

3.1 

8.9 

86, 827 


Table  2  compares  fatal  and  non-fatal  accidents  for  the  State  and 
the  district. 

A  comparison  of  this  district  with  all  the  other  districts  of  the 
State  combined,  as  given  in  Table  6,  shows  that  District  I  has  fewer 
fatalities  per  ton  of  coal  mined  or  per  1,000  employees,  but  has  almost 
twice  as  many  non-fatal  injuries  per  1,000  employees,  and  produces  less 
than  one-third  as  many  tons  of  coal  per  non-fatal  injury.  Including 
both  fatal  and  non-fatal  accidents  the  district  has  17.8  per  1,000  em- 
ployees as  compared  with  11.4  for  all  other  districts  combined.  In  both 
fatal  and  non-fatal  accidents  the  percentage  caused  by  falling  rock  or 
coal  greatly  exceeds  the  percentage  from  this  cause  in  the  remainder  of 
the  State;  and  in  non-fatal  accidents  this  discrepancy  is  marked,  the 
ratio  being  as  67.8  to  38.2.  This  high  percentage  of  accidents  for  the 
district  is  due  principally  to  inability  to  enforce  proper  spragging  of 
the  coal  and  propping  of  the  roof  at  the  face.  Unless  compelled  to  mine 
properly  the  miner  will  pull  the  coal  down  with  a  pick,  or  will  wedge  it 
down  after  he  has  undermined  2  to  8  inches.  He  does  not  consider  it 
necessary  to  sprag  the  coal  for  this  short  undermining,  and  is  often 
injured  when  the  unsupported  coal  falls  away  suddenly. 

A  comparison  of  production  per  employee  is  given  in  Table  7  for 
each  of  the  11  mines  examined,  for  District  I  and  for  all  the  other 
districts  of  the  State  combined. 


MINING   PRACTICE 


27 


Table 


-Per  capita  production  of  employers 


Number 


Employees 


O  c3 


3  *  n 


>»p 


1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

All  mines  in  District  I 
All  other  districts 
combined l 


33 
40 
33 
10 
9 
10 
11 
26 
17 
40 
25 
902 

5,576 


570 
400 
279 
216 
160 
375 
376 
300 
121 
400 
510 
10, 632 

59, 297 


518 
320 
225 
200 
150 
340  I 
291 
260 
104 
325 
448 
8,510 

44,  808 


603 

1,450 

17.3 

6.1 

43.9 

2.5 

440 

900 

10.0 

2.7 

22.5 

2.3 

312 

750 

8.5 

2.6 

22.7 

2.7 

226 

550 

21.6 

i .  i 

55.0 

2.5 

169 

400 

17.7 

7.9 

44.4 

2.5 

385 

900 

37.5 

(.  o 

90.0 

2.4 

387 

800 

34.2 

3.0 

72.8 

2.1 

326 

700 

11.5 

3.9 

26.9 

2.3 

138 

200 

7.1 

3.1 

11.7 

1.6 

440 

1,000 

10.0 

2.8 

25.0 

2.5 

535 

1,200 

20.4 

5.2 

48.0 

2.3 

,534 

24, 299 

10.7 

2.8 

26.9 

2.4 

,873 

301,  845 

10.6 

2.2 

54.1 

5.1 

2.8 
2.8 
3.3 
2.8 
2.7 
2.7 
2.8 
2.7 
1.9 
3.1 
2.7 
2.8 


2.4 
2.2 
2.4 
2.4 
2.4 
2.3 
2.0 
2.1 
1.4 
2.3 
2.2 
2.1 


1  Shipping  mines  only  during  the  year  ending  June  30,  1912. 

VENTILATION 

The  ventilation  of  mines  operated  on  the  longwall  system  presents 
few  difficulties,  and  the  problem  of  supplying  air  to  the  men  at  the 


Overcasts  shown  thus:    X 
Curtains  shown  thus.-     — 

Fig.  14.     Plan  showing  direction  of  ventilating  current.    (After  Swift) 


28 


COAL    MINING    INVESTIGATIONS 


working  face  is  easy  of  solution.  In  room-and-pillar  mining,  the  faces 
of  the  rooms,  that  is,  the  working  places  of  the  miner,  are  outside  the 
direct  flow  of  the  air  current  except  when  the  face  of  a  room  is  at  the 
point  where  a  cross-cut  is  driven  through  the  room-pillar.  In  longwall 
mines  the  air-current  always  flows  along  the  working  face,  as  shown 
by  fig.  14.  More  physical  discomfort  is  suffered  by  the  longwall  miners, 
however,  because  the  temperature  at  the  face  of  longwall  mines  is 
greater  than  at  the  face  of  room-and-pillar  mines.  This  is  shown  in 
Table  8  which  gives  return  air  temperature  for  mines  worked  under 
both  systems. 

Table  8. — Comparative  temperatures 


Average 

Average 

Number 

tempera- 

tempera- 

Degrees 

weeks 

ture  at 

ture  at 

of  heating  in 

Location 

Mining  svstem 

of  daily 

bottom  of 

bottom  of 

passage 

readings 

intake 

return 

through 

air  shaft — 

air  shaft — 

mine 

degrees  F 

degrees  F 

Oglesby 

Longwall 

39 

52.2 

74.0 

21.8 

LaSalle 

..do  .... 

47 
40 

58.3 
53.9 

76.9 
64.9 

18.6 

Benton 

Room-and-pillar 

11.0 

Glen  Carbon... 

..do .. 

44 
43 

56.9 
55.3 

68.0 
75.5 

11.1 

Average  for  longwall 

Average  for  room-and-pillar. 

20.2 

Room-and-pillar 

42 

55.4 

66.5 

11.1 

This  table  shows  that  during  passage  through  the  workings  of  a  long- 
wall  mine  of  average  size  the  ventilating  current  undergoes  an  average 
rise  in  temperature  of  20.2  degrees  above  that  at  the  bottom  of  the 
downcast  shaft.  In  a  room-and-pillar  mine  of  ordinary  extent  of  work- 
ings the  air  current  has  its  average  temperature  raised  11.1  degrees  F. 
while  passing  through  the  mine.  This  average  difference  throughout 
the  year  of  9.1  degrees  between  the  temperatures  of  longwall  and  room- 
and-pillar  mines  is  largely  because  in  the  former  a  much  smaller 
quantity  of  air  with  lower  velocity  passes  over  more  men  and  lamps. 
Sometimes  the  gob  fires  in  longwall  mines  increase  the  temperature. 
When  mining  is  done  in  the  clay  under  the  coal  few  gob  fires  occur 
because  then  not  much  coal  finds  its  way  into  the  gob.  Gob  fires  are 
more  frequent  where  undermining  is  done  in  the  coal.  Every  condition 
necessary  for  spontaneous  combustion  is  then  found  in  the  gob  about  15 
feet  from  the  face : 

Fine  particles  of  coal. 

Finely  divided  ircn  pryites. 

Moisture. 

Air  confined  in  the  interstices  of  the  gob. 

Initial  heat  produced  perhaps  by  roof  pressure  on  the  gob. 

Where  the  gob  is  not  heated  to  the  point  of  combustion  its  temperature 
may  be  raised  considerably  by  the  oxidation  of  coal  and  pyrites.  Because 
the  presence  of  air  is  necessary  for  this  process  gob  fires  do  not  occur 
much  further  than  twenty  feet  behind  the  face  as  beyond  this  point  the 
settling  of  the  roof  has  packed  the  gob  so  tightly  that  air  is  excluded. 
That  sufficient  heat  is  developed  by  a  few  gob  fires  to  bring  about  the 
increased  temperature  at  the  longwall  face  is  shown  by  readings  in 
Table  9  taken  at  the  face  10  feet  from  a  gob  fire  after  the  air  current 


MINING    PRACTICE  29 

has  passed  the  sealed-off  fire,  and  also  by  readings  taken  at  the  face  100 
feet  distant  from  the  fire  before  the  current  has  passed  over  it. 


Table  9. — Temperature  readings  near  gob  fire 

Location 

Temperature 
degrees  F. 

Face  one  hundred  feet  towards  intake  from  fire 

73 

Ten  feet  beyond  fire 

84 

The  cost  of  removing  sulphur  from  the  mine  varies  from  %  to  1% 
cents  per  ton  of  coal  mined.  Fires  in  the  gob  of  longwall  mines  are 
easily  sealed  off.  The  usual  method  is  to  build  around  three  sides  of  a 
fire  a  solid  wall  of  roof  rock  leaving  the  gob  which  has  been  packed  by 
roof  settling  as  the  fourth  side.  A  lining  of  fine  sand  is  placed  inside 
of  the  wall. 

The  sand  is  usually  brought  into  the  mine  for  this  purpose  and 
stored  underground  to  be  ready  for  immediate  use  when  needed.  In- 
cluding cost  of  sand  the  expense  of  sealing  off  a  small  gob  fire  approx- 
imates $25.  In  some  mines  road  dust  instead  of  sand  is  used  for  sealing 
off  fires  and  serves  the  purpose  as  well  because  road  dust  consists  prin- 
cipally of  inert  shale  pulverized  by  car  wheels  on  the  track  and  by  the 
feet  of  men  and  animals  on  the  roadways.  If  a  fire  occurs  from  5  to  20 
feet  from  the  face  between  two  rooms,  it  is  reached  in  some  mines  by 
digging  through  the  burning  gob  which  is  then  loaded  oul  if  possible  be- 
fore sealing  off  is  begun.  This  method  of  walling  off  is  regarded  as 
very  efficient  because  the  sand  or  road  dust  packs  remain  effective  for  ;it 
least  two  months;  and  before  the  end  of  this  period  the  fires  are  ex- 
tinguished. 

Very  little  marsh  gas  is  found  in  longwall  mines,  although  occa- 
sional pockets  are  discovered  in  small  sand  deposits  immediately  above 
the  shale  roof.  Whenever  it  thus  occurs  it  is  quickly  diffused  in  the  air 
and  become-  so  dilute  that  no  cap  is  shown  by  a  testing  lamp. 

Eoof  falls  caused  by  the  expansion  and  contraction  of  roof  material 
on  account  of  temperature  change-  are  numerous,  because  cracks  extend 
several  feet  into  the  immediate  roof.  Two  of  the  mines  examined  beal 
the  intake  air  in  winter  to  keep  the  temperature  more  constant  and  also 
to  prevent  the  formation  of  ice  in  the  intake  shaft.  The  amount  of  roof 
fall  is  in  this  way  lessened.  In  one  of  these  mines  the  exhaust  steam 
from  the  fan  engine  is  put  into  the  downcast  air  shaft  through  a  1-inch 
pipe;  and  as  ;i  precautionary  measure  againsl  a  temperature  so  low  thai 
exhaust  steam  could  not  keep  the  shaft  free  from  ice.  a  l'/.-inch  pipe 
for  live  steam  also  runs  int..  the  -haft.  It  is  seldom  necessary,  however, 
to  use  this  live  steam.  In  the  other  mine  the  live  steam  is  sent  down 
the  intake  shaft  through  a  3-inch  pipe,  which  leads  to  a  cylindrical  radia- 
tor 7  feet  in  diameter  placed  at  the  bottom. 

The  necessity  for  artificial  humidification  to  prevent  coal-dust  ex- 
plosions has  not  been  apparent  in  longwall  mines.  Inasmuch  as  nil  the 
coal  is  removed  from  the  seam  as  the  face  advances  ami  as  the  excava- 
tion is  tilled  with  waste  rock  the  only  sources  of  supply  for  coa]  are  the 
daily    working    face   of    fresh    coal    and    the   spillings    from    the    pit    r;\v*. 


30 


COAL    MINING    INVESTIGATIONS 


In  room-and-pillar  mines  the  ribs  of  the  entire  workings  and  sometimes 
also  the  roof  and  floor  are  of  coal ;  and  the  spalling  of  this  coal  furnishes 
a  cumulative  supply  of  dust  that  becomes  constantly  drier  and  more 
explosive.  The  coal  dust  from  mining  at  the  face  in  the  longwall  mines 
is  covered  with  shale  and  clay  within  a  few  days  after  it  is  made  so  that 


Fig.  15.    An  entry  closely  timbered.     (Photo  by  J.  J.  Rutledge) 

there  is  no  accumulation  of  it.  The  dust  brushed  from  the  ribs  of  long- 
wall  mines  is  not  inflammable.  The  analyses  of  samples  thus  taken 
show  that  the  dust  consists  principally  of  shale  or  other  inert  matter. 
Table  10  gives  the  average  of  analyses  and  of  pressures  developed  in  the 
explosibility  apparatus  for  14  samples  of  longwall  rib  dust  collected  in 
the  haulage  ways. 

Table  10. — Comparison  of  longwall  and  room-and-pillar  rib  dust  on 

haulage  ivays 


Mining  system 

Number 
samples 

Proximate  analysis  of  coal — First:    "  As 

received"  with  total  moisture.    Second: 

•'Dry"  or  moisture  free 

Pressure  in 
pounds  per 
square  inch 
developed 
in  explosi- 
bility flask 
at  2192°  F. 

Moisture 

Volatile 
matter 

Fixed 
carbon 

Ash 

Average  longwall 

14 
3 

/       3.45 
I       Dry 

f       5. 54 
I       Dry 

14.68 
15.19 

34.  89 
39. 94 

6.77 
7.01 

39.21 
41.51 

75.12 
77.80 

20.  37 

21.  56 

0.175 

Typical    room-and-pillar    mine    in 
southern  111  inois 

4.760 

MINING    PRACTICE 


31 


The  high  average  temperature  of  the  air  in  longwall  mines  de- 
creases the  relative  humidity  and  considerable  moisture  is  absorbed 
from  the  dust  of  ribs  and  roads  so  that,  unless  additional  moisture  is 
supplied  by  seepage  water  or  by  sprinkling,  the  dust  of  the  roadways 
becomes  very  dry.  In  a  few  mines  of  this  district  the  haulage  roads 
are  sprinkled  at  intervals  varying  from  one  week  to  three  months. 


Fig.  It3.    Cog  built  of  props 

The  work  performed  by  the  ventilating  fan  was  determined  by  a 
water  gage  at  5  of  the  mines  examined.  The  readings  varied  from  1.7 
to  2.5  inches.  By  a  provision  of  the  State  law  effective  /Inly  1,  1913, 
water  gages  must  be  installed  in  all  mines. 

Table  11  gives  data  covering  ventilating  equipment  at  the  mines 
examined  in  this  district. 


Table  11. — Ventilating  equipment 


No. 
mine 


Depth  of 

air  shaft 

in  feet 


Clear 
dimensions  of 
air  shaft  in  feet 


Number 
compart- 
ments 


Fan 


Diameter 

in  feet 


Length 

in  feel 


Material  of  fan  house 


Water 
gage  read- 
ings 
iu  inches 


1 

413 

2 

Slope 

3 

398 

4 

546 

5 

135 

6 

100 

7 

200 

8 

300 

*9 

Slope 

10 

480 

li 

530 

9  x  12 

2 

14 

8 

8  x  12 

2 

10 

4 

5  x    9 

2 

8 

4 

X  x  10 

2 

20 

10 

6  x  12 

2 

20 

6 

10  feet  diameter 

1 

16 

4 

8  x  10 

2 
2 
1 

1 

(i    X      () 

10 

}      » 

/                    ")    X      f) 

i             0x7 

4 

8  x  12 

2 

16 

6 

:»  x     9 

2 

20 

6 

Brick 

Frame 

Corrugated  iron 

Concrete 

Frame 

Brick  and  concrete 

Brick,  steel  and  concrete. 


Frame 

Brick  and  concrete. 
Brick 


2.0 
No  gage 
No  gage 

No  gage 
2. 5 

No  gage 
1.9 

1.7 

No  gage 
No  gage 


*  Two  air  shafts. 


32 


COAL    MIXING    INVESTIGATIONS 


TIMBERING 

The  continual  subsidence  of  the  strata  overlying  the  coal  in  longwall 
mines  makes  timbering  of  roadways  difficult  and  expensive.  Permanent 
timbering  can  be  extended  only  to  that  point  where  the  first  rapid  and 
violent  subsidence  has  ceased,  and  it  is  not  usual  to  extend  permanent 
timbering  to  any  point  until  the  face  has  been  advanced  beyond  it  for  at 
least  two  years.  Roof  breaks  destroy  the  cohesion  of  the  shale  and  large 
masses  of  rock  must  be  supported  by  timber  so  that  the  collars  of  the 
three-piece  gangway  set  must  be  heavier  than  those  ordinarily  used  in 
room^and-pillar  entries.  For  usual  timbering  with  ordinary  roof  con- 
ditions an  8-inch  cross  bar  is  supported  by  6-inch  legs.     These  are  bat- 


Fig.  17.    Sketch  of  branch  cog 


tered  iy2  inches  for  each  vertical  foot  between  rail  and  cross  bar.  Under 
bad  roof  the  entry  is  usually  closely  timbered  as  shown  in  fig.  15.  The 
frames  in  this  photograph  have  white  oak  legs  8  inches  in  diameter,  and 
10-inch  white  oak  cross  bars.  These  frames  are  spaced  on  6-foot  centers, 
and  the  top  and  sides  of  the  entry  are  lagged  with  split  and  round  props 
4  to  5  inches  in  diameter. 

When  it  is  necessary  to  support  the  increased  area  of  roof  resulting 
from  turning  off  a  cross  entry  from  the  main  entry,  or  from  turning 
rooms  from  a  cross  entry,  cogs  are' built  with  props  as  shown  in  fig.  16. 
A  sketch  showing  details  of  these  cogs,  called  "branch  cogs,"  is  given 


MINING    PRACTICE 


33 


in  fig.  17.  These  cogs  are  filled  two-thirds  full  of  waste  rock  and  mining 
dirt.  It  is  necessary  to  allow  for  subsidence  of  the  overlying  strata  which 
crushes  the  cog,  as  the  weight  comes  on  it.  A  cog  built  4  feet  high  above 
the  floor  will  in  18  months  be  crushed  to  a  height  of  but  18  inches  above 
the  floor.  If  cogs  were  entirely  filled  with  waste  rock  and  dirt  they 
would  offer  too  much  resistance  to  roof  subsidence  and  the  roof  would 
"cut"  at  the  cog.  This  roof  caving  would  increase  the  danger  of  acci- 
dents from  roof  falls  and  would  add  to  clean-up  expense. 

Article  V  of  the  Third  Vein  District  Agreement  states :  "The  price 
for  turning  a  room  where  the  company  does  the  brushing  and  builds  the 
cog  shall  be  $5,  and  where  the  miner  does  the  brushing  and  builds  the 
cog  the  price  shall  be  $8,747,  the  company  to  have  the  option  of  method/' 

Besides  the  branches  at  entry  and  room  junctions  two  other  wide 
roof  areas  must  be  supported,  that  is,  the  shaft  bottom  and  the  lyes  called 


FIG.  18.     A  typical  lye 


partings  in  room-and-pillar  mines.  In  this  district  the  timbering  of  the 
bottoms  does  not  generally  differ  from  the  timbering  of  bottoms  in  room- 
and-pillar  mines.  The  roof  is  supported  by  props  alone,  by  timber-sets, 
by  masonry,  or  by  steel  I-beams.  In  one  mine  in  which  pillar  coal  was 
removed,  after  roof  and  floor  met  the  bottom  was  widened  and  timbered 
with  10  by  12-inch  frames  spaced  on  4-foot  centers  and  lagged  with  3  by 
12-inch  planks.  No  trouble  from  root'  cutting  has  ever  beer  experienced 
in  this  mine. 

In  a  few  mines  the  inner  lyes  are  in  abandoned  rooms  but  generally 
the  lye  is  formed  by  widening  the  entry  at  the  desired  location.  The 
usual  width  of  a  lye,  as  shown  in  fig.  IS,  is  11  feel  ;  ten-inch  collars  and 
legs  are  used  for  the  timber  sets  which  are  spaced  6  feel  apart.  This 
lye  is  75  feet  long  and  provides  storage  for  13  cars  on  cacli  track. 


34 


COAL    MIXING    INVESTIGATIONS 


The  high  temperature  of  the  return  air  current  in  this  district  is 
very  favorable  to  fungus  growth;  the  heavy  and  expensive  entry  timbers 
on  the  return  fail  through  decay  in  from  2  to  4  years.  In  one  mine  of 
the  district  preservative  treatment  is  given  to  the  timber  used  on  the 
main  roads.  At  this  mine  the  life  of  an  untreated  white  oak  collar 
averages  two  years  on  the  intake  and  less  than  one  year  on  the  return. 
Treated  timbers  have  already  been  in  service  on  the  return  for  three 
years  without  sign  of  decay.  The  timbers  to  be  treated  are  peeled  and 
sun-seasoned.  Before  taking  them  underground  they  are  painted  with 
a  heavy  coat  of  carbolineum.  The  cost  of  labor  and  carbolineum  for 
treating  two  legs  7  feet  long  and  6  inches  in  diameter,  and  one  collar 
6  feet  long  and  7  inches  in  diameter,  is  16  cents.  The  cost  of  the  un- 
treated timbers  is  45  cents. 

Where  a  soft  wet  fire  clay  several  feet  thick  underlies  the  coal  it 
is  sometimes  necessary  to  build  short  cogs  as  a  foundation  for  the  legs 


Fig.  19.    Circular  hoisting  shaft 


of  the  frames  in  the  lyes.  A  cog  of  4-inch  props  is  usually  constructed 
3  feet  high  and  4  feet  square.  On  the  top  of  this  cog,  a  3  by  12-inch 
plank  4  feet  long  is  placed.  The  bottom  of  the  leg  rests  in  a  notch  cut 
in  this  plank.  As  the  roof  weight  settles  on  the  frames  the  cog  is  pushed 
into  the  clay  and  the  settling  is  gradual  and  continuous. 

The  cost  of  timbering  in  a  district  where  conditions  of  roof  and  floor 
are  so  widely  different  varies  with  each  mine.  Total  cost  of  timbering  at 
the  11  mines  examined  varied  from  5  to  8  cents  per  ton  of  coal  mined. 
At  that  mine  in  which  the  total  cost  of  timbering  was  8  cents,  the  cost 
of  face  props  was  6  cents  per  ton  of  coal  mined.  A  mine  producing  1,450 
tons  a  day  employed  8  day-timbermen  and  used  daily  1,500  props;  70 
cross  bars,  7  feet  in  length;  50  bars,  8  feet  in  length;  and  2  bars,  10 


MINING    PRACTICE  35 

feet  in  length.  Props  3y2  or  4  inches  in  diameter  are  usually  bought. 
From  .5  to  1  cent  per  linear  foot  is  paid  for  props;  the  number  used  per 
ton  of  coal  mined  varies  from  iy2  to  3.  The  expense  of  cross  bars  in- 
creases rapidly  with  increased  diameter  and  length  of  span.  Table  12 
gives  average  cost  in  the  district  of  mine  timbers  of  various  diameters 
and  lengths.  These  figures  do  not  include  the  cost  of  placing  in  posi- 
tion but  refer  only  to  the  timbers  as  piled  on  the  surface. 


Table  12. — Cost  of  mine  timbers 


Length 

Diameter 

Average 
cost 

Feet 
6 

Inches 
8 
8 
10 
10 
12 

Cents 

15 

7 

16 

7 

80 

10 

125 

14 fc 

190 

Shaft  linings  are  generally  of  timber,  but  concrete  is  also  used.     One 
of  the  earliest  concrete-lined  shafts  built  in  the  countrv  is  at  the  Xo.  6 


;  9  >.,'  *                      *'■    -j   y,. .»,  ' 

Hi    JKe^aEKB 

*»4  -V     -,'■  '.:■'■! 'Np-'-       ■■IP 

•'»  JH| 

R 

B 

■PL'                          ■• ' 

5t» 

,  4i   r«Bra 

\       r      • 

|i  p/M  20^^  V9s^v  ^SO 

Amount  of  "company  brushing"  necessary  after  subsidence 


mine  of  the  Big  Four  Wilmington  Coal  Company  at  Coal  City.  Two 
circular  shafts  were  sunk,  one  of  which,  the  air  shaft,  LO  feci  in  diameter, 
was  finished  in  May,  1903.     The  hoisting  shaft,  13  feet   in  diameter  as 


36 


COAL    MIXING    INVESTIGATIONS 


shown  in  fig.  19,  was  completed  in  June,  1903.  Both  of  these  shafts 
were  lined  with  concrete  14  inches  thick  from  rock  40  feet  deep  to  a 
point  8  feet  above  the  surface  level,  making  a  total  of  48  linear  feet  of 
concrete  lining. 

HAULAGE 

The  older  mines  in  the  district  were  opened  when  mechanical  haul- 
age was  not  in  general  use.  Mules  are  still  used  for  moving  the  coal 
from  the  face  to  the  bottom  in  many  of  these  mines,  although  the  face 
may  be  over  a  mile  from  the  hoisting  shaft.  A  tendency  to  supersede 
mules  by  mechanical  haulage  is  apparent  in  this  district.  Several  mines 
are  arranging  for  the  installation  of  electric  locomotives. 

At  present  locomotives  are  found  in  only  3  of  the  36  mines  in  this 
district;  rope  haulage  in  3  mines.     Mules  are  used  both  for  main  and 


Fig.  21.    Typical  shaft  bottom 


secondary  haulage  in  29  mines  and  in  one  pit  cars  are  pushed  to  the  bot- 
tom by  men.  The  costs  of  haulage  and  maintenance  of  haulage  ways 
are  high  per  ton  of  coal  because  from  y±  to  V3  of  the  entire  tonnage 
hauled  to  the  bottom  is  waste.  Furthermore,  the  continuous  settling 
of  the  roof,  and  in  many  mines,  the  heaving  of  the  floor,  add  an  expense 
for  brushing  roof  and  floor  which  is  not  an  item  in  room-and-pillar  mines. 
The  roadways  are  usually  maintained  4  feet  high  and  7  to  9  feet  wide. 
The  miners  brush  the  roof  at  the  face,  but  the  settling  as  the  face 
advances  necessitates  a  further  brushing  which  is  done  in  the  LaSalle 
field  by  the  company.  Fig.  20  shows  the  amount  of  "company  brushing" 
necessary  at  one  mine  after  subsidence.  This  brushing  of  roof  and 
floor  costs  the  operators  in  the  LaSalle  field  approximately  15  cents  per 
ton  of  run-of-mine  coal.  Labor  for  haulage  costs  approximately  12^2 
cents.    Maintenance  of  mules  and  car  repairing  costs  51/?  cents.   The  total 


MINING    PRACTICE 


37 


cost  items  chargeable  to  haulage  and  maintenance  of  haulage  roadways 
amount  to  about  33  cents  in  a  typical  mine  with  mule  haulage  on  both 
main  and  cross  entries.  The  thin  bed  and  narrow  entries  limit  the 
height  of  cars  and  the  capacity  of  the  pit  car  generally  used  in  the 
district  is  small.  The  average  weight  of  pit  cars  used  in  the  11  mines 
was   900   pounds 


The   light   weight   of   pit   cars   and   the   slow   speed 


Fig.  22.     Receiving  hopper  at  shaft  bottom 

attained  by  the  trips  allow  a  comparatively  Light  rail;  a  1  (3-pound  rail 
is  in  some  mines  used  in  the  entries  and  a  12-pound  rail  in  rooms. 
Table  13  gives  haulage  statistics  for  the  11  mines  examined.  Pit  cars 
are  not  generally  kept  in  good  repair  but  in  many  mines  are  leaky. 
Fig.  21  shows  a  shaft  bottom  in  the  vicinity  of  Coal  City. 


Table  13. — Underground  haulage 


No. 

mine 


Kind  of  haulage  through 
main  entries 


Track 
gage 


Rail  weight 


Main 


Second- 
ary 


Pit  cars 


Weight 
empty 


Capacity 


Ratio 
of  load  to 

weight 

of  empty 

car 


Percent- 
age of 

empty  car 
weight 
in  total 

weight   of 

car  and 

load  j 


Mule 

Third  rail  electric  locomo- 
tive  

Mule 

Main  and  tail  rope 

Mule 

Main  and  tail  rope 

Main  and  tail  rope 

Electric  locomotive 

Mulei 

Mule 

Electric  locomotive 


33 

lti 

hi 

1,800 

2,600 

1.44 

37 

lti 

12 

840 

2,200 

2.62 

42 

lti 

lti 

900 

2,  .-.00 

2.77 

26£ 

It) 

lti 

900 

1.700 

1.88 

36 

hi 

lti 

125 

1,000 

2.  3.'. 

24 

20 

12 

825 

2, 000 

2.  43 

32 

lti 

hi 

500 

1,000 

2.00 

36 

30 

lti 

1,100 

2,  700 

2.  45 

37 

24 

12 

850 

1,000 

1.17 

42 

lti 

12 

1.200 

2,650 

2.21 

36 

3.-> 

16 

1,  100 

2,600 

2.  36 

40.9 

27.6 
26.  5 
34.  6 

2*.).  S 
29.  2 
33.  3 
28.9 
45.9 
31.2 
29.7 


Cable  on  slope. 


38 


COAL    MINING    INVESTIGATIONS 


HOISTING 

The  daily  production  of  mines  in  the  district  is  comparatively 
small;  the  average  daily  tonnage  of  the  11  mines  examined  varies  from 
200  to  1,450.  Hoisting  speed  is  lower  than  in  some  districts  because 
the  amount  of  coal  daily  raised  to  the  surface  does  not  necessitate  high 
speed.  A  greater  number  of  hoists  is  made  daily  than  the  figures  for 
coal  production  disclose  because  about  one-third  as  much  rock  as  coal 
is  taken  to  the  surface.  In  one  mine  having  a  coal  production  of  1,450 
tons  a  day  1,400  hoists  a  day  are  made.  The  shaft  is  413  feet  deep. 
Eaising  waste  rock  to  the  surface  requires  350  of  these  hoists. 

None  of  the  mines  examined  had  automatic  caging  at  the  bottom, 
and  the  self-dumping  cage  was  found  at  only  one  mine  in  the  district. 
Here  an  adaptation  of  ore  skip  is  used.     Pit  cars  from  the  face  on 


i 

PL    \       v 

1         «fl 

til 

1 

1 

jit 

r    •    J;/i 

|1    ,,; 

""■•   :'-y-.  : 

WHE»    **:- 

Fig.  23.    Skip  adjusted  to  hoist  men 


reaching  the  shaft  bottom  have  their  contents  dumped  as  shown  in  fig. 
22  into  a  two-compartment  hopper  9  feet  deep  lying  below  the  floor. 
Each  compartment  of  the  hopper  has  a  capacity  of  two  pit  cars,  and 
automatically  discharges  its  contents  into  the  skip.  The  skip  is  pro- 
vided with  a  vertically-sliding  door  which  is  automatically  lifted  in  the 
tipple,  discharging  the  contents  of  the  skip  on  to  the  screens.  The  skip 
can  be  adjusted  to  hoist  men  as  shown  in  fig.  23.  Weighing  is  done  at 
the  bottom.  Hand  caging  and  hand  unloading  are  common  at  the 
smaller  mines,but  the  steam  ram  and  transfer  table  are  used  in  the 
tipple  in  the  larger  mines.  This  method  of  automatic  unloading  is  not 
general  in  Illinois. 


MINING    PRACTICE 


39 


At  several  mines  in  the  district  cages  built  to  hold  two  pit  cars 
tandem  were  used  as  shown  in  fig.  24. 


Fig.  24.     Tandem  cage 


At  the  mines  examined  all  but  one  of  the 
direct  connected  with  cylindrical  drums.    Table  1-i  gives  hoisting  data  tor 
the  11  mines  examined. 


Table  14. — Hoisting  equipment 


Aver- 

No. 

age 

mine 

dailv 

tonnage 

Type  of 

cage 


Hoisting  shaft 


Depth 


Size  in 
feet 


Kind  of  lining 


Num- 
ber of 
com- 
part- 
ments 


Hoisting  engine 


Firs!   or 
second      Size 
motion 


Drum  - 


Diam- 
eter in 

feel 


Length 

in  feet 


150 


750 
550 

ion 


700 

200 

1,000 

1,200 


Tandem  plat- 
form   

Platform 

Platform 

Skip 

Platform 

Platform 

Platform 

Self  dumping 


Tandem  plat- 
form   

Platform 


413 

12  x  12 

465 

Six  12 

398 

9  xl2 

546 

7  xl2 

135 

6  Xl2 

100 

*13 

200 

7   x  lti 

300 

7  x  16 

Slope 

6x8 

480 

12  x  16 

530 

9  x  12 

Timber 

..do 

..do 

..do 

..do 

Concrete  and 

t  Lmber 

Timber 

..do 

..do 

..do 

..do 


2 

First . . . 

24    x   12 

8 

2 

..do.... 

24  x  36 

li'. 

2 

..do.... 

20  x  32 

8 

2 

..do.... 

13*X  42 

.) 

2 

..do.... 

18  x  36 

8 

3 

..do.... 

14  x  20 

:'.'. 

2 

..do.... 

lti  x  30 

:"> 

2 

..do.... 

32  x  12 

s 

1 

Second. 

14  x  20 

ti 

2 

First . . . 

24  x42 

8 

2 

..do.... 

24  x  12 

8 

*  Diameter;  circular  shaft, 
a  Largest  diameter  if  conical. 


40 


COAL    MIXING    INVESTIGATIONS 


PREPARATION  OF  COAL 

The  amount  of  lump  coal  over  ±14  inches  made  in  proper  longwall 
mining  is  15  to  20  per  cent  higher  on  the  average  than  is  made  in  room- 
and-pillar  mines,  but  when  shooting  is  allowed  in  longwall  work  the 
percentage  of  lump  coal  is  not  so  large.  In  this  district  the  amount  of 
l1/^  inch  lump  as  reported  by  the  mine  operators  varies  from  65  to  83 
per  cent.  In  those  mines  where  no  shooting  is  allowed  the  coal  breaks 
in  large  blocks. 

At  several  of  the  mines  in  the  district  the  following  sizes  of  coal 
are  made  at  the  tipple : 

Name  Size 

Lump Over  6  inches 

Chunk Over  3£  inches,  through  6  inches 

Egg Over  1J  inches  through  3J  inches 

Screenings Through  1 J  inches 


Four  of  the  11  mines  examined  send  their  screenings  to  washeries 
where  a  further  separation  is  made  into  3  sizes. 

Name  Size 

No.  1  nut : Over  1  inch,  under  1^  inches 

No.  2  nut Over  |  inch,  under  1  inch 

Slack Under  I  inch 


Two  mines  shipped  run-of-mine  coal  only 


Table  15. — Tipple  equipment 


Materia]  of 
tipple 

Primary  sizing  screen 

Rescreened  or 
washed  coal 

No. 
mine 

Type 

Screening  surface 

Inclin- 
ation 

Shakes 

per 
minute 

Per  cent 
of  lump 
coal    over 

Length  in 
feet 

Width 
in  feet 

l\  inches 

1 
2 

Timber 

Timber 

Shaking 

..do... 

24 
43 
34 
27 
57 
22 
24 
48 

6 
6 
6 
6 
6 
6 
6 
6 

1  in  4 
1  in  4 
1  in  4 
1  in  4 
1  in  4 
1  in  4 
1  in  4 
1  in  4 

120 
85 

110 
80 
80 
90 

120 
75 

Neither 

..do 

80 
83 

3 

..do... 

..do 

Rescreened 

Washed 

..do 

..do 

Neither 

79 

4 

Timber.. . 

do     . 

65 

5 

..do 

70 

6 

8 

Timber 

Timber  and  steel. 
Steel 

..do 

..do 

..do 

80 
*73 
*73 

J9 

Timber 

10 

Steel 

Shaking 

..do 

50 

8 

5 

1  in  5 
1  in  5 

60 
60 

Both 

f83 

11 

Washed 

83 

*  Over  1J  inches. 
t  Over  |  inch. 
X  Run-of-mine. 

Table  15  gives  data  on  coal  preparation  at  each  mine.  The  surface 
plants  of  the  district  are  not  generally  so  compact  as  the  average  surface 
plant  of  a  room-and-pillar  mine.  Fig.  25  shows  a  representative  tipple 
of  the  district.  The  comparatively  small  outputs  do  not  require  rapid 
continuous  hoisting  and  consequently  the  power  plants  of  the  11  mines 
are  comparatively  small. 

Table  16  contains  data  on  power  plant  equipment  at  each  mine 
visited. 


41 


42 


COAL    MINING    INVESTIGATIONS 


Table  16. — Power  plant  equipment 


Car 
storage 
above 
tipple 

Number 
loading 
tracks 

Boilers 

Electric  generators 

Number  mine 

Number 

Total 
H.  P. 

Average 

steam 

pressure 

K.  W. 

Volts 

1 

50 

25 
10 
15 
10 
50 
20 
25 
9 
80 
20 

4 
4 
2 
3 
3 
3 
3 
3 
1 
3 
3 

6 
6 
4 
2 
4 
2 
6 
3 
2 
6 
9 

900 
720 
600 
300 
300 
300 
200 
800 
200 
900 

90 
115 

90 
106 

85 
140 

75 
100 

90 

90 
112 

2 

3...     .             

125 



275 

4 

100 

250 

5 

6.. .                                

8 

9                         

150 

i2o' 



250 

10 

250 

11...                  



PUBLICATIONS  OF  THE  ILLINOIS  COAL  MINING 
INVESTIGATIONS 


Bulletin  1.  Preliminary  Report  on  Organization  and  Method 
of  Investigations,  1913. 

Bulletin  2.  Coal  Mining  Practice  in  District  VIII  (Danville), 
by  S.  O.  Andros,  1914. 

Bulletin  3.  A  Chemical  Study  of  Illinois  Coals,  by  Prof  8.  W. 
Parr,  1914 

Bulletin  4.  Coal  Mining  Practice  in  District  VII  (Mines  in 
bed  6  in  Bond,  Clinton,  Christian,  Macoupin, 
Madison,  Marion,  Montgomery,  Moultrie,  Perry, 
Randolph,  St.Clair,  Sangamonr  Shelby  and 
Washington  counties),  by  S.  O.  Andros,  1914. 

Bulletin  5.  Coal  Mining  Practice  in  District  I  (Longwall),  by 
S.  O.  Andros,  1914. 


